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A Paradox In Running Paces

The running literature usually suggests that marathons be run faster than ones LSD pace. However, I ran four marathons at a pace that was slower than my LSD pace. I'm not sure I understand this seeming paradox in running-paces, but I thought I'd explain my history and give a hypothesis I have about this.

When I started running, at age 38, my pace was about 14 minutes per mile. I had a long range goal of running marathons, but that goal was far off and fuzzy in my mind. I just ran for the enjoyment of running. I ran that way for several years, slowly increasing my distance while running a comfortable LSD pace. I eventually reached 24 miles per week, running three 6-mile runs and two 3-mile runs. One day I decided it was time to get serious about running marathons, and I started to extend my Saturday 6-mile run into a long run. During this time I continued to run a comfortable LSD pace, but I didn't think about how fast I was going. I just enjoyed myself.

One day I wondered how fast I was going, and I measured my pace. To my surprise, I was running 8-minute miles. Over a several year time, I had advanced from 14-minute miles to 8-minute miles! I continued to run LSD as I advanced my long run to 15 miles. Once I reached 15 miles, I continued that weekly long run year around. I was surprised to discover that my LSD pace for my running, including the 15-mile long run, was now about 7-minute miles!

I chose the Green Mountain Marathon in Vermont (I was living in Massachusetts) as my first marathon, and I added one mile per week to my long run and continued that until I had run a 20-miler. During that time I discovered that I could continue my 7-minute pace for about 18 miles before I started getting tired.

As I tapered to the day of the marathon, I knew I couldn't maintain the 7-minute pace for the full 26.2 miles so I decided to run the marathon at a 8:30 pace, hoping the slower speed would conserve energy that would help me finish the last 6 or 7 miles of the race. That slower pace did help, but at 20 miles I ran out of energy and had to jog/walk the last 6 miles. I finished the marathon with approximately a 9-minute average pace, and I felt fine at the end of the race.

About a month after the marathon I ran a 10K and finished in 40+ minutes, a pace of about 6:30. During the next couple of years I ran several 5-mile races at a pace of about 6:30. During those races, I ran as fast as I could and still maintain the pace for the full race. Thus, 6:30 was close to my maximum speed.

In recap, here is what happened.

My comfortable LSD pace advanced from about 14 minutes to 7 minutes over an 8-year period in which I ran nothing but the LSD pace. No speed training during that time.

After I reached 7 minutes for my LSD pace, my maximum speed was probably a little bit faster than 6:30

I started each of my four marathons at a 8:30 pace and finished with an average pace of about 9 minutes.

Notice the pattern. My comfortable LSD pace was slightly less than my maximum speed. My marathon pace was significantly less than my LSD pace. Even though the running literature recommends that a marathon pace be run significantly faster than ones LSD pace, I had reversed that relationship.

Here is my hypothesis about this. This hypothesis was formed by looking at the trends of the paces during my 8-years of LSD running and my completion of four marathons. I have no actual data to confirm or contradict this hypothesis.

During the 8 years of LSD running, my LSD pace advanced towards a pace that was natural for my body, and my LSD pace became a fast pace.

My marathon pace was less than my LSD pace. This seems strange to experienced marathoners, but it is a result of my LSD pace being so fast. From the viewpoint of energy, I didn't have enough energy to complete the marathon at my fast LSD pace, so I ran the race at a slower pace to conserve energy, energy that would be needed during the final part of the marathon.

What does all of this mean? I don't know, but it is interesting. I think the most important part of this is the idea that our LSD pace will increase as our bodies get stronger. Given enough time in running LSD, a person can become quite fast without doing traditional speed training. That is an important thing to realize since traditional speed training increases the risk of injury.

6 comments:

I've been wondering if this effect is because your slower running still burns more energy for the same distance (i.e. running at a 10 minute pace means you burn energy for 50 minutes for a 5 mile run, compared to 40 minutes at an 8 min pace - you burn less energy per minute at a 10 min/mile pace, but you have to go for 10 more minutes so overall you burn more energy?).

I've been in the Army for the last 18 years and they like you to exercise, so I have been running for awhile, but just started training for my first marathon. I've noticed when I try and run my long runs slower that I actually have trouble running farther than when I run at a quicker pace. Which got me thinking about it - glad I found your post!

Your comment, "slower running still burns more energy for the same distance" has me thinking.

If I had run the marathon at my normal LSD pace of 7-minute miles, the 17 miles would have taken me 119 minutes instead of the 138 minutes I actually spent. I would have had to slow down during following three miles. Supposed I slowed to an 8.5 minute pace. I would have run that three miles in the same time I actually ran it. Then, suppose I would have jogged/walked the last 6 miles at the same average pace that I did it in real life. Under these assumptions I would have run my marathons about 19 minutes faster than I ran them in real life.

I could have slowed to a 9.5 mile pace during those three miles and still have run the marathons 16 minutes faster. Interesting. I wish I could go back in time and run the marathons differently to see what would happen.

On the other hand, runners are cautioned about going out too fast in the beginning and not having enough energy left to finish the race at that pace and thus having to slow down during the last half of the race.

What's counter intuitive is that people would do tons of training for a huge event where they'll do something they never have -- longer and faster. The trend I see is to prepare for months at paces that support continued training, then go ahead and "let it all out" on race day and take some recupe time after. What is not counter intuitive to me is that increasing my distance significantly at my current fitness level slows my pace and increasing my speed shortens the run. So what would I expect if I tried both -- failure. Now, cut my distance a lot and I may very well take flight mission control! Your experience seems normal to me brother. If others get a different experience, there's a difference in training or experience. My current regimen sounds like what you described -- lot of LSD that got fast -- and I would never expect to increase both speed and distance and succeed as I usually only ever increase distance. Sound about right?